Processes for preparing certain hexaazaisowurtzitanes and their use in preparing hexanitrohexaazaisowurtzitane

ABSTRACT

A heavy-metal-free sequence leading to a superior, more economical, and scalable process for the high efficiency conversion of hexaallylhexaazaisowurtzitane (HAllylIW) to hexanitrohexaazaisowurtzitane (CL-20).

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a divisional application, claiming the benefit of, parentapplication Ser. No. 11/789,678 filed on Apr. 23, 2007 now U.S. Pat. No.7,875,714, whereby the entire disclosure of which is incorporated herebyreference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

The invention described herein may be manufactured and used by or forthe government of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor.

FIELD OF THE INVENTION

One of the most important new energetic compositions for ordnanceapplications is hexanitrohexaazaisowurtzitane (CL-20), but itsproduction process suffers from several economic and environmentaldisadvantages, mostly related to requirements for benzylamine startingmaterial and for heavy metal (typically, palladium) catalysts. It isdesirable to prepare the hexaazaisowurtzitane cage in a form that isdirectly nitrolyzable to CL-20 without a requirement for expensivebenzylamine starting material or heavy metal catalysts. Embodiments ofthe invention relates to processes for preparing certainhexaazaisowurtzitanes and their use in preparinghexanitrohexaazaisowurtzitane that does not require benzylamine startingmaterial or heavy metal catalysts, thus introducing a new, lower-cost,less wasteful, and environmentally cleaner process to produce CL-20.

BACKGROUND OF THE INVENTION

The recent publication by French researchers (Cagnon, G.; Eck, G.;Hervé, G.; Jacob, G. U.S. Patent Appl. 2004/0260086 (2004); Hervé, G.;Jacob, G.; Gallo, R. Chem. Eur. J. 2006, 12, 3339) that the synthesisscheme originally proposed by Nielsen (Nielsen, A. T.; Nissan, R. A.;Vanderah, D. J.; Coon, C. L.; Gilardi, R. D.; George, C. F.;Flippen-Anderson, J. J. Org. Chem. 1990, 55, 1459) yieldshexaallylhexaazaisowurtzitane (HAllylIW) provided us the opportunity toexplore the potential of HAllylIW for use in new routes for thesynthesis of hexanitrohexaazaisowurtzitane (CL-20). With respect to thesynthesis of HAllylIW, however, it is important to note that we haveconfirmed that the scheme devised by Nielsen of condensation of certainprimary amines with glyoxal to produce hexaazaisowurtzitane derivativesreadily forms HAllylIW in solution when allylamine is condensed withglyoxal. However, under the conditions prescribed by Nielsen, noprecipitate of HAllylIW is formed. We believe that the absence of such aproduct precipitate may have contributed to Nielsen's inability toisolate HAllylIW from the reaction of allylamine with glyoxal. Thisfailure of HAllylIW to precipitate may have been the predominant factorcontributing to Nielsen's erroneous conclusion that his efforts toextend the isowurtzitane synthesis to amines of this type wereunsuccessful, notwithstanding that allylamines were expected to producehexaazaisowurtzitanes.

SUMMARY OF THE INVENTION

Embodiments of the invention demonstrates new routes to CL-20 that meetthe desired criteria of avoiding benzylamine starting material and heavymetal catalysts. It employs less expensive allylamine starting materialand uses an alkali-metal strong-base catalyst. Heretofore, all syntheticroutes used to prepare the hexaazaisowurtzitane cage for production ofCL-20 have depended on the condensation of benzylamine with glyoxal,originally developed by Nielsen, as noted above. CL-20 has remainednearly prohibitively expensive, however (as a potential large-scalereplacement for the explosive ingredientoctahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), for example),due mainly to the high cost of benzylamine starting material and ofhydrogenolysis steps involving palladium catalyst used in thedebenzylation of hexabenzylhexaazaisowurtzitane (HBIW) intermediate inthe course of preparing acylhexaazaisowurtzitane intermediates,including tetraacetyldiformylhexaazaisowurtzitane (TADF),tetraacetylhexaazaisowurtzitane (TADA or TADH or TAIW), orhexaacetylhexaazaisowurtzitane (HAIW).

The by-product of hydrogenolytic debenzylation of HBIW, toluene, is noteconomically or cleanly reconverted to benzylamine (only viachlorination followed by amination), so benzyl is not a clean,recoverable protecting group in that system. Various researchers ((a)“Lower Cost, Improved Quality CL-20 Energetic Material”;https://www.dodmantech.com/successes/Navy/weapons/weapons_LowerCostCL20_(—)120805.pdf;(b) Wardle, R. B.; Hinshaw, J. C. U.S. Pat. No. 6,147,209 (2000); (c)Wardle, R. B.; Hinshaw, J. C. U.S. Pat. No. 7,129,348 (2006); andreferences therein) have addressed process development for reducing thecost of CL-20 production, but have not approached cost reduction bydeveloping a fundamentally different synthetic route to thehexaazaisowurtzitane cage such as is disclosed by the present invention.

In the work disclosed here, we have applied the chemical transformationof base-catalyzed isomerization of allylamines into 1-propenylamines toknown hexaallylhexaazaisowurtzitane (HAllylIW) (using potassiumtert-butoxide base) to prepare a new derivative,hexa(1-propenyl)hexaazaisowurtzitane (HPIW). (This new derivative shouldnot be confused with hexapiperonylhexaazaisowurtzitane, also designatedHPIW by Tsai, H. -J. et al. Hua Hsueh [Chemistry] (Taipei) 2003, 61,199.) We employed photooxygenation of HPIW by singlet oxygen—usingoxygen gas photolyzed by a quartz halogen lamp in the presence of atetraphenylporphine sensitizer—in order to oxidize some of the1-propenyl substituents to formyl substituents. Although the oxidationreaction did not go to completion to producehexaformylhexaazaisowurtzitane, the partially oxidized product—apolyformylhexaazaisowurtzitane—underwent nitrolysis to form CL-20 in aclean reaction. The nitrolysis of this intermediate is more efficientthan direct nitrolysis of HAllylIW. Furthermore, we demonstrate that thenew intermediate HPIW undergoes direct nitrolysis to form CL-20. Thisreactivity of the enamine HPIW is explainable as a mechanisticallyreasonable transformation.

DETAILED DESCRIPTION OF THE INVENTION

All synthetic routes used to prepare the hexaazaisowurtzitane cage forproduction of CL-20 depend on the condensation of benzylamine withglyoxal, originally developed by Nielsen, as referenced above. As notedabove, CL-20 has remained nearly prohibitively expensive mainly due tothe high cost of benzylamine starting material and of hydrogenolysissteps involving palladium catalyst used in the debenzylation ofhexabenzylhexaazaisowurtzitane (HBIW) intermediate in the course ofpreparing acylhexaazaisowurtzitane intermediates.

An alternative benzylamine-free route to a hexaacylhexaazaisowurtzitaneprecursor to CL-20 was envisioned following the recent report by Hervéet al. (SNPE France) of a preparation of hexaallylhexaazaisowurtzitane(HAllylIW) from allylamine and glyoxal ((a) Cagnon, G.; Eck, G.; Hervé,G.; Jacob, G. U.S. Patent Appl. 2004/0260086 (2004); (b) Hervé, G.;Jacob, G.; Gallo, R. Chem. Eur. J. 2006, 12, 3339). The new route weenvisioned was to utilize HAllylIW in a well-known isomerizationreaction of allylamines into 1-propenylamines. The resultinghexa(1-propenyl)hexaazaisowurtzitane could then be oxidized by singletoxygen (which may be generated by dye-sensitized photolysis of oxygengas, for example) via another well-known transformation: cleavage of theC═C bond of propenylamines to produce formamides (Foote, C. S.; Lin, J.W. -P. Tetrahedron Lett, 1968, 3267). The resultinghexaformylhexaazaisowurtzitane is another example of the class ofhexaacylhexaazaisowurtzitanes that may be susceptible to directnitrolysis to CL-20.

Following several failed attempts to reproduce the allylamine-glyoxalreaction according to conditions reported by Hervé et al., wewere—through some process development—able to successfully recoverHAllylIW by significantly modifying the isolation conditions reported byHervé et al. (cf. Experimental Section). Thus, HAllylIW has beenprepared by us in 33% yield, better than the 20-25% reported by Hervé etal.

The required rearrangement of HAllylIW was achieved (Equation 1) bybase-catalyzed isomerization (Price, C. C.; Snyder, W. H. TetrahedronLett 1962, 69). Clean, efficient isomerization of HAllylIW tohexa(1-propenyl)hexaazaisowurtzitane (HPIW) was effected—essentiallyquantitatively—by potassium t-butoxide (t-BuOK) base in dimethylsulfoxide (DMSO) at room temperature in about 6 hours (also at 80° C. inabout ¼ hour). We also demonstrated that the isomerization wasefficiently achieved by introducing potassium t-butoxide as itsconveniently available tetrahydrofuran solution into a solution ofHAllylIW in DMSO or in dimethylformamide (DMF). Reactions in such about1:1 solvent mixtures typically proceeded to completion in an overnightrun. However, tetrahydrofuran (THF) as the sole solvent did not allowisomerization at room temperature, even on prolonged reaction. As inprevious similar transformations of this type ((a) Sauer, J.; Prahl, H.Tetrahedron Lett, 1966, 2863; (b) Carlsen, P. H. J.; Jorgensen, K. B. J.Heterocycl. Chem. 1997, 34, 797), the allylamine-to-propenylamineisomerizations require only catalytic t-butoxide; some of our successfulruns employed ⅓ equivalent of potassium t-butoxide per allylsubstituent.

HPIW was most easily purified (sufficiently for subsequent reactions) byremoving solvent(s) under high vacuum and redissolving the HPIW in asuitable solvent in which residual potassium t-butoxide is insoluble. Weinitially chose benzene-d₆ for the sake of characterizing the dissolvedHPIW and subsequent reaction products by NMR. Potassium t-butoxide hassufficiently low solubility in benzene that this is an effectivepurification method. However, other hydrocarbon solvents in whichpotassium t-butoxide has low solubility, including toluene or xylene oreven some aliphatics, are suitable for this process.

From analyses of four solutions of t-butanol—potassium t-butoxidemixtures in DMSO-d₆—quantified by integration of the quaternary carbonabsorptions vs. those of DMSO-d₆ (i.e., all non-protiatedcarbons)—linear regression of a plot of mole fraction of t-butoxide vs.quaternary carbon chemical shift produced the following relationship,useful for determining potassium t-butoxide content in DMSO-d₆ solutionsby ¹³C NMR:X _(t-BuO) ⁻ =49.17−δ₁₃ _(C) ^(quat)/1.36This regression estimates a chemical shift of δ 66.87 for pure t-butanolin DMSO-d₆, comparing very favorably with a literature value of δ 66.88.

The ¹H and ¹³C NMR spectra of HPIW in various solvents indicate that itexists in a few (two to four) rotational isomers (rotamers) due tocis-trans isomerism of the propenyl substituents and restricted rotationabout the N-propenyl bonds. Other examples of exo-heterocyclic enamines,N,N-dimethylaminomethylene-substituted pyrazoles, exhibit complex NMRspectra due to rotamers, as well (Kölle, U.; Kolb, B.; Mannschreck, A.Chem. Ber. 1980, 113, 2545).

HPIW was next subjected to oxidation by singlet oxygen, generated byhalogen-lamp photolysis of oxygen gas, sensitized by catalytic amountsof zinc tetraphenylporphine (Equation 2). The transformation of enaminesto formamides via photooxygenation has been reported to occur in avariety of different solvents (Foote, C. S.; Dzakpasu, A. A. TetrahedronLett. 1975, 1247.).

The crude oxidation product (6) is shown in Equation 2 as ahexaazaisowurtzitane cage with indeterminate numbers of formyl,1-propenyl, and saturated polymer chain substituents and where n isindeterminate (0≦n), 0≦x≦6, 0≦y≦6, and 0≦x+y≦6. Integration of thevarious broad absorptions of the ¹H NMR spectra suggested that theaverage extent of oxidation of 1-propenyl substituents to formyl wastypically between three and four substituents per hexaazaisowurtzitanecage (i.e., x=about 3 or 4) before significant precipitation may haveprevented further oxidation.

Table 1 lists the variety of conditions that were attempted to effectphotooxygenation of HPIW to polyformylhexaazaisowurtzitane derivatives.

TABLE 1 Conditions of photooxygenation of HPIW Solvent systemTemperature Reaction time C₆D₆ R.T. 3 h 2:1 C₆D₆-acetone-d₆ 0° C. 8 h3:5 CDCl₃—CD₂Cl₂ 0° C. 3 h 1:1 C₆H₆—DMSO-d₆ 0° C. 3 h acetone-d₆ dryice-EtOH bath 6 h 1:5 CD₂Cl₂—CDCl₃ dry ice-EtOH bath 0.8 h  

The products of some photooxygenation reactions were subjected tonitrolysis after isolation from reaction suspensions by removal of allvolatiles (solvent and acetaldehyde by-product). An initial runutilizing a mixture of about 98% nitric acid and acetonitrile-d₃produced a minor amount of CL-20 (<10%)—confirmed by HPLC analysis aswell as ¹H and ¹³C NMR spectrometry—in a complex mixture after 6 days ofreaction at ambient temperature. (Such prolonged reaction conditionssignificantly hydrolyzed acetonitrile ultimately to acetic acid.) Inanother run, the very viscous oily residue from a photooxygenationreaction was subjected to nitrolysis conditions using about 98% nitricacid in the presence of Nafion NR50 beads as a strong Brønsted acidcatalyst (Equation 3). Nafion® resins are perfluorinated ion-exchangematerials composed of carbon-fluorine backbone chains and perfluoro sidechains containing sulfonic acid groups. Nafion NR50 is a polymer of thegeneral structure:

The application of Nafion® resins as versatile heterogeneous catalystsin organic transformations has been well established (Aldrich TechnicalBulletin AL-163 and references therein). Other known strong Brønstedacid catalysts may be screened for efficiency in promoting thisconversion, and those being efficacious will be suitable replacementsfor Nafion NR50.

Reflux of the reaction solution for a total of about 30½ hours resultedin a surprisingly clean conversion of the crude polyformyl intermediateto CL-20. CL-20 is the predominant constituent in the spectral regionattributable to hexaazaisowurtzitane species.

In parallel with the success of the nitrolysis of a crude product (6) ofphotooxygenation of HPIW, an experiment to directly nitrolyze HPIWitself was carried out. Out of concern for possible hydrolysis ofenamine HPIW—which could lead to disruption of the cage and degradationof intermediates—from the minor water content of the about 98% nitricacid, fuming sulfuric acid was added to nitric acid to ensure anhydrousconditions for nitrolysis. An aliquot of the reaction mixture after 4hours' reflux, added to dichloromethane-d₂ for NMR analysis, showedsignificant CL-20 content. The mixture was not quite as clean as thenitrolysis of the photooxygenation product of HPIW, but neither had thenitrolysis reaction proceeded as long.

We have discovered that displacement of substituents on thehexaazaisowurtzitane cage is superior to nitrolysis of α-unsubstitutedalkyl derivatives (example, would be formed by initial nitration ofallyl substituents in HAllylIW). For example, in the reports of Hervé etal. of new hexaazaisowurtzitanes, treatment of 1 g of HAllylIW withmixed acid produced a yellow solid (whereas CL-20 is colorless or white)that contained a detectable amount of CL-20, but no yield was specified.In contrast, the isomerization disclosed here on HAllylIW produces moreeasily removed substituents—following their initial nitration inHPIW—and the content of CL-20 in the nitrolysis mixture is high. Wespeculate that transient intermediates of β-nitration of HPIW could bemixed polynitropoly(α-substituted β-nitropropyl)hexaazaisowurtzitanes(Equation 4, wherein 0≦x≦6, and X=NO₂, etc.). (X=H, such as with simplenitric acid, would leave α-hydroxy sites susceptible to furthernitration by the nitrating reagent, still forming nitrolyzableintermediates with X=NO₂.)

Examples and Supporting Data

Hexa(1-propenyl)hexaazaisowurtzitane (HPIW) (Procedure A).Hexaallylhexaazaisowurtzitane (HAllylIW) was prepared as reported byHervé et al. (following Nielsen as discussed above) with the significantmodification that the product solution was basified with saturatedaqueous NaHCO₃ and then stored at −16° C. for two days, therebyprecipitating HAllylIW. The HAllylIW precipitate was filtered off anddried further by dissolving it in CH₂Cl₂, drying over MgSO₄, filtering,and removing the solvent. To 5 mL of a solution of 204 mg HAllylIW (0.50mmol) in DMSO-d₆ was added 224 mg (2.00 mmol) of solid potassiumt-butoxide. The mixture was magnetically stirred in a capped vial atambient temperature. Progress of the isomerization was monitoredoccasionally by ¹H NMR analysis of small aliquots and was seen to becomplete with essentially quantitative conversion after 6 h. The ¹H NMR(DMSO-d₆) spectrum of HPIW in the crude reaction mixture: δ 1.52-1.63(m, CH₃), 4.24-4.33 (m, CHCH₃), 4.84 (s, 4 H, cage CH), 4.89 (s, 2 H,cage CH), 5.88-5.96 (NCH).

Similarly, the ¹³C NMR (DMSO-d₆) spectrum of the crude reaction mixture:δ 11.78, 11.89, 12.20, 15.08, 74.07, 76.61, 77.14, 81.02, 82.11, 82.60,92.75, 100.24, 100.96, 101.62, 101.77, 102.51, 134.84, 135.30, 135.46,135.58.

HPIW was separated from residual potassium t-butoxide by pumping offDMSO-d₆ under high vacuum at room temperature, redissolving HPIW inabout 25 mL benzene, filtering off insoluble salt (and minor possiblepolymeric by-products), removing benzene under vacuum at roomtemperature, and redissolving in CD₂Cl₂. ¹H NMR (CD₂Cl₂): δ 1.59-1.70(m, CH₃), 4.42-4.76 (m, CHCH₃), 4.75 (s, 4 H, cage CH), 4.84 (s, 2 H,cage CH), 5.93-6.02 (NCH). ¹³C NMR (CD₂Cl₂): δ 12.46, 12.57, 12.82,15.49, 75.67, 75.81, 77.95, 78.30, 78.71, 78.85, 78.94, 81.92, 82.48,83.35, 83.89, 95.45, 102.85, 103.78, 104.38, 104.87, 105.90, 135.47,135.59, 135.76, 135.88, 136.09.

Hexa(1-propenyl)hexaazaisowurtzitane (HPIW) (Procedure B). To 1 mL of asolution of 204 mg HAllylIW (0.50 mmol) in DMSO-d₆ was added 1.0 mL of 1M solution of potassium t-butoxide in tetrahydrofuran, and the mixturewas magnetically stirred in a capped vial at ambient temperature. After18 h, isomerization of HAllylIW to HPIW was complete. Again, HPIW wasseparated from residual potassium t-butoxide by pumping off DMSO-d₆under high vacuum at room temperature, redissolving HPIW in about 25 mLbenzene, filtering off insoluble salt (and minor possible polymericby-products), removing benzene under vacuum at room temperature, andredissolving in CD₂Cl₂; and the isolated product was identical by ¹H NMRand ¹³C NMR to the final product of Procedure A.

Photooxygenation of HPIW (Example). The HPIW product from anisomerization by Procedure B, following extraction into benzene andconcentration, was redissolved in 6 mL of acetone-d₆ in a 10-mLgraduated cylinder (with a standard-taper joint) fitted with a Claisenadapter to allow inlet as well as egress of an oxygen purge via a glasscapillary. A few mg of zinc(II) tetraphenylporphine sensitizer was addedto the solution, and the base of the cylinder was submerged in a dryice—ethanol bath. With a purge of oxygen passing through, the solutionwas irradiated with a quartz halogen lamp. After 6 h of treatment, apale pink flocculent solid was suspended in the solution. Arepresentative sample of the suspension was withdrawn for NMR analysisafter adding DMSO-d₆ to dissolve it. (Acetaldehyde by-product wasclearly apparent in the ¹H NMR spectrum of the crude reaction mixtures.)¹H NMR (about 1:1 acetone-d₆—DMSO-d₆) of the hexaazaisowurtzitaneproduct (6): δ 1.0-1.4 (bm, CH₃), 3.3-6.9 (bm, all CH), 8.1-8.5 (CHO).After filtration of the precipitate from acetone-d₆ and drying undervacuum over P₄O₁₀, the product was a pale peach colored solid.

Nitrolysis of oxidation product 6 to CL-20. The product suspension of aphoto-oxygenation reaction of HPIW was concentrated to dryness undervacuum and pumped under high vacuum at room temperature overnight. Thevery viscous oily residue in a round-bottom flask—fitted with anaddition funnel containing 15 mL of cold about 98% to about 100% nitricacid (Fluka “100%” nitric acid) and a nitrogen bubbler—was cooled in adry ice—ethanol bath. The nitric acid was added quickly via the additionfunnel. When the nitric acid started to freeze, the cooling bath wasremoved, and the organic reactant dissolved in the acid upon warmingadventitiously. After reaching room temperature, the solution was heatedto reflux—with a nitrogen bubbler atop the reflux condenser—in an oilbath maintained at 85-95° C. After 8½ h reflux, NMR analysis of analiquot showed little conversion to CL-20, so several beads of NafionNR50 were added. Reflux was resumed and continued for a total of 30½ h.An aliquot of this crude reaction solution withdrawn intoacetonitrile-d₃ surprisingly showed, by ¹H NMR, very clean conversion ofall hexaazaisowurtzitane species to CL-20. By-products of nitrolysis ofthe substituents from 6 are also fairly simple in the spectrum. ¹H NMR(CD₃CN with HNO₃) of crude CL-20: δ 7.81 (s, 2 H), 7.91 (s, 4 H).

Nitrolysis of HPIW to CL-20. Purified product solution (in benzene) froma preparation of HPIW by Procedure B was evaporated to dryness undervacuum. 10 mL CCl₄ was added, and the solution was again evaporated todryness under vacuum. The residue in a round-bottom flask—fitted with anaddition funnel containing 11 mL of cold about 98% to about 100% nitricacid (Fluka “100%” nitric acid) and a nitrogen bubbler—was cooled in adry ice—ethanol bath. The nitric acid was added quickly via the additionfunnel. When the nitric acid started to freeze, the cooling bath wasremoved, and the organic reactant dissolved in the acid upon warmingadventitiously. After stirring while warming for 1 h, about 1 mL of 30%fuming sulfuric acid was added, and the solution was heated toreflux—with a nitrogen bubbler atop the reflux condenser—for 4 h. Asample withdrawn into dichloromethane-d₂ showed, by ¹H NMR, significantsimplification of the hexaazaisowurtzitane region and formation ofCL-20, confirmed by addition of a small amount of authentic CL-20 to theNMR sample and observation of the increase of specific peaks. ¹H NMR(CD₂Cl₂ with HNO₃, vs. trimethylsilylpropionic-d₄ acid as δ 0.00) ofcontained CL-20: δ 7.11 (2 H), 7.45 (s, 4 H).

While the invention has been described in connection with what arecurrently considered to be the most practical and preferred embodiments,it is to be understood that the invention is not to be limited to thedisclosed embodiments, but to the contrary, is intended to cover variousmodifications, embodiments, and equivalent processes included within thespirit of the invention as may be suggested by the teachings herein,which are set forth in the appended claims, and which scope is to beaccorded the broadest interpretation so as to encompass all suchmodifications, embodiments, and equivalent processes.

1. A process for preparing a compound represented by the Formula (B)comprising: providing a compound of the structure (A)

reacting the compound of structure (A) with anhydrous nitric acid;extracting a reaction product of the structure (B)


2. A process for preparing hexanitrohexaazaisowurtzitane comprising:dissolving hexa(1-propenyl)hexaazaisowurtzitane in anhydrous nitric acidto form a first composition; refluxing said first compositionnitrolyzing hexa(1-propenyl)hexaazaisowurtzitane to form a secondcomposition containing hexanitrohexaazaisowurtzitane; and, extractinghexanitrohexaazaisowurtzitane from said second composition.
 3. A processfor preparing hexanitrohexaazaisowurtzitane comprising: dissolvinghexa(1-propenyl)hexaazaisowurtzitane in cold about 98% nitric acid toform a first composition; chilling said first composition to thefreezing point of said nitric acid; warming said first composition toambient temperature with stirring to form a second composition; addingfuming sulfuric acid to form a third composition; refluxing said thirdcomposition under nitrogen until nitrolysis ofhexa(1-propenyl)hexaazaisowurtzitane is substantially complete to form afourth composition containing hexanitrohexaazaisowurtzitane; and,extracting hexanitrohexaazaisowurtzitane from said fourth composition.